Mali - Tuareg rebels Wednesday said they had seized control of a northeastern region in Mali as UN chief Ban Ki-moon urged an end to the fighting amid growing global concern over the unrest.

  "We took Tinzawaten on Wednesday," said Mohamed Ag Ghaly, a Tuareg rebel fighter, referring to an area near the Algerian border.

  "Our troops are occupying the town," he said, speaking on the telephone. "We will give details about deaths and prisoners later."

  A Malian official confirmed the rebel claim, saying: "We asked our troops as a strategic measure to abandon their positions in Tinzawaten."

  He added that "there were no deaths and no fighting."

  "One of our current strategies is to abandon isolated positions," the official said, speaking on condition of anonymity.

  Ban meanwhile was "deeply concerned" over civilian casualties and the humanitarian impact of the conflict, said his spokesman Martin Nesirky.

  More than 20,000 people have fled from northern Mali into neighbouring Burkina Faso, Algeria and Mauritania, according to the UN.

  The battle between Tuareg rebels and government forces is "aggravating an already dire humanitarian situation throughout the Sahel region," said the UN spokesman.

  Ban called on the rebel groups "to immediately cease their attacks and to engage in dialogue with the government of Mali to resolve their grievances." He offered UN support for efforts to find a peaceful solution.